Footing Drain Question?

joasis

Ok....I am not experienced in basements....we build nearly everything slab on grade, or crawl space. Now I have a customer I am estimating a new home for that will have a walk out basement, approximately 35 wide (into the hillside) by 70 feet long. We will do this in an ICF, so I will have footings and a stem wall....and the ICF estimator and I discussed this, and he thinks I need a "form a drain" system, very expensive, and I think since it is a higher elevation, a simple 4 inch perforated PVC with gravel pack, or 6 at most, surrounding and a foot lower then the stem wall will suffice.....both ends open toward a pond another 15 feet lower in elevation. In this same thought, I am thinking with the area, it may be wise to place two 4 inch area drains, splitting the floor area by thirds......Opinions? Suggestions? I may be way out in left field, but I want to have the plan firmly in mind before the city inspector (ex-drywall contractor) can run a hatchet job on it.

Also, the site is virgin soil, natural hill that was flattened for a slab on grade home, and they bought enough to encompass the natural pond......going to be a beautiful home, and this is one I will enjoy.

__________________

Chris Johnson

Joasis;

Form-a-drain is a nice product, albeit expensive material wise, figure your labour costs and it may be a wash, I don't know what you pay your labourers to install 4" big-O vs. forming the foundation/footing.

My personal preference is the Big-O, probably because I am old school, I started this way and continue to do so to this day, also the footing boards I remove within a few hours of the pour, scrape the concrete off and they become my bucks for the window and door openings in the ICF build, provided you use PT lumber for the footings.

I have a bad habit of over waterproofing basements, I don't want a leak, and neither do you. Call this overkill, but here it goes...

After ICF is poured, apply a peel and stick membrane, followed by Delta-MS foundation wrap, or whatever comparable product is available in your area, 4" Big-O w a sock beside the footing as well as on top of the footing, secure it all in place using scraps of rebar from the ICF wall.

On the inside use the same Big-O w a sock around the interior of the footing, and I usually run a few across the floor area just in case hydrostatic pressure ever becomes and issue. A sump pit needs to be installed and both the interior and exterior weeping tile needs to be connected to it.

On a walkout basement I still put in the sump pit, but keep it at the high side, it is now a back up just in case the day light drain you speak of gets plugged up (Small Animals, etc.)

When all this is done, bring in the stone slinger and fill the basement and compact as needed and I like at least 2 1/2' high on the walls and same on the ground for the exterior.

Seems to be a lot of work, but what does a call back cost you?

__________________
Chris

mdshunk

Around here, most guys are switching to Form-a-drain's. Trouble is, they're staking the formadrain right though the top of the whole thing. That's inviting silt buildup and clogged foundation drains.

K2

In my county Engineers are required for soils testing, foundation design, and perimeter drains, and it usually costs about 600 bucks total. I guess i'm used to it. I don't see why any builder would stick his neck out designing this stuff to save $600.

I understand that basements are not common in OK and I'd be curious if there might be a good reason??

Positive fall on a perimeter drain for me and it doesn't take much. I don't want the slightest bit of ponding around the foundation.

rino1494

Form-a-drain sucks. I've dealt with it a few times and every mason I talk to hates it. You save time by not stripping it, but it takes twice as long to form. IMO......a 4' pvc pipe is better than the form-a-drain. As far as height, it should be no higher than the top of the footer. One big misconception with footer drains is that people think that they need to have pitch. Water levels itself out and the footer drains can be level with no pitch and they will work fine with no problems. Even with heavy rain storms. As far as installing (2) 4" pipes, unless there is a stream running through the excavation, it is a waste of money.

__________________
Life is hard. It is harder when you are stupid

Uncle Sam wants YOU....to speak ENGLISH

K2

Water will be perfectly level but the rest of the world is not. Put a half inch dip in my drain and i have a half inch of water trying to mess with my bearing soil. I want pitch.

rino1494

The excavation for the footers are level. If you don't want your footer drains level, then you need to pitch your excavation towards the ditch out to daylight. I don't think the masons would like all of that extra concrete. What does it matter if the ditch out to daylight is pitched, but the drains around the footers are not.

As a matter of fact, you don't even need a pipe around your footers. As long as you have gravel, the water will drain through the gravel and out a gravel ditch. The pipe is there just for capacity and to give the water a nice place to flow.

__________________
Life is hard. It is harder when you are stupid

Uncle Sam wants YOU....to speak ENGLISH

K2

Our drain guys dig a about a 4" trench with 3"/100' fall then visqueen over hot moped to the wall. Takes a couple guys about 15 minutes for the trench. That's the way all the engineers around here draw it and the only way it will pass inspection.

concretemasonry

Only in Colorado where nothing is level and everything drains in the wrong direction.

Why would a sane person slope a perforated drain tile?

I think your are talking about a prescriptive code requirement (nutty?), but that is what you have to live with. In the rest of the world, perforated tile around a foundation should be installed level with the perforations at 4 and 8 o'clock. That way, the pipe will drain without the associated problems that cause much bigger problems caused by the slopes.

Do you realize that the 3" of drop per 100' around a home can cause the water to be drained more from some soil than others and then you have your typical expansive clay problems that cause differential movement. You want uniform conditions under a foundation.

Someone in the mile-high country should consider the difference between collecting water around a foundation and transporting water in a solid pipe.

__________________
Dick

Engineer, designer and consultant recently active domestically and internationally on construction and design in about 35 countries.

K2

I know. Building was so easy back in NJ, SC, and NC. Then I came here and put some dirt in a jar and added water and watched the jar break. Well it's been interesting anyway.

joasis

There were many more basements done 50 years ago, then today, and that was when, I suppose, since slab on grade wasn't popular, it was a no brainer to go ahead and do the excavation. Land here is inexpensive also....so homes tend to spread out, rather then be on tight lots where the room needs to be utilized......my guess.

Also, the ground just does not freeze in Oklahoma, so heave isn't a problem.....slab on grade probably accounts for 98% of new home construction.

__________________

Driftwood

Same detail as Dick said, LEVEL ,HOLES DOWN. On hills,outfall 12ft. down hill from found.

woodmagman

Do what you know...a walk out is very functional. Ground water will kill any good basement. The "form a drain" seems to have the concept. Using any product that you will likely not use on a regular basis is risky. You are very comfortable forming with the forms you have on hand today. Why risk time loss for something new when the gain is so little.
Waterproofing is the only thing between the grounds natural pressures and your finished basement.

ch0mpie

Maybe I'm missing something but soil conditions and ground water elevation are going to be major factors in what kind of system you use.

Driftwood

Death valley is a snap. Swamp foundations need special care.

I imagine ,we're discussing average conditions ,We encounter.
Care to elaborate on some of Your more interesting situations? We are all here to learn! Thank's Drift

ch0mpie

I can't say I've encountered too many interesting situations. If the proposed basement slab is found to be with in 2' of the groundwater table, the basement will typically be elimated because of the cost of dewatering the excavation during construction, and because the basement will never really be dry dispite spending a lot of money try to make it dry.

If it doesn't matter if the basement gets a little water, or they are only conserned with rain water, I see most guys using crushed stone with perferated pipes under the slab to a sump pit. Ussually a water proofing membrane put on the basement walls and a geo-composite is applied on top of the membrane.

There is a lot to average between death valley and a swamp, helps a lot to know which way your leaning Hope this helps.

Driftwood

Hadn't thought about Your 2 ft. rule. Will think about that in the future